Join the Facebook group Ball Python People for more info.

Here is the complete process to setting up a proper 20 gallon tank for a ball python, between 500g (preferably 800g) and 2500g.
My little piece of tape on the cool side has the wrong symbol for "less than 90°". It should have been a less than sign , not greater than.

If you get to my UTH/Thermostat speech, and decide not to use one (tldr; UTHs need thermostats, and if you can't buy a good thermostat, don't use a UTH at all), the timestamp to skip ahead is 14:23
If you want to use one and are able to get a quality thermostat, watch all the way through.

MATERIALS:
20 gallon LONG tank
Screen
Screen clips
2 Reptile Basics medium hides
Large ceramic water dish
2 Acurites
Clutter of your choice
8.5 Flukers dome with dimmer
150w CHE
Heat mat
Herpstat 1 thermostat
Blackout material of your choice
Reptichip substrate
HVAC foil tape

88° air, 90° surface on hot side
82° air, less than 90° surface on cool side
Humidity between 5575, 6570 ideal.